Dedicated or shared IP address for email sending

The focus of this article is to answer whether you should choose dedicated or shared IP addresses to send your company's marketing and transactional emails from.

Let us establish first of all that our views and recommendations in this article concern emails sent via what is commonly called an Email Service Provider (ESP) – a company specialising in sending emails on behalf of other companies.

The emails we are talking about in this article are therefore marketing emails and transactional emails such as newsletters, automated marketing mails, order confirmations and so on.

The factors that apply to personal mail from individuals within a company are not covered in this article.

The first, and perhaps most important, factor is whether you know who you are sharing IP addresses with, if you use shared IPs.

The great majority of ESPs are large companies with thousands of customers. That means that with a shared IP address from one of the large ESPs, an individual company knows very little about the many other companies it shares IP addresses with.

That starting point is the background for most general recommendations, where experts advise companies sending a lot of email to use dedicated IP addresses rather than shared ones.

What counts as "a lot of email" in this context also varies a great deal depending on who is speaking. Some suggest dedicated IP addresses from as little as 50,000 emails a month, while others talk about 250,000 emails a month as the threshold.

At the general level we agree that companies sending very large volumes can consider using dedicated IP addresses – but our recommendation to our own customers starts from a different place than the general one.

In international terms Yulsn is a small "Premium Email Service Provider".

We currently send emails on behalf of around 50 customers from our own SMTP server, hosted in a Danish hosting centre. Although we are small internationally, we send many millions of emails every month and have many years of experience ensuring good delivery.

• All our customers send high-quality emails with high response rates.

• No customer gets access to send emails before we – together with the customer – have made sure the technical setup is entirely in order, including that both SPF and DKIM are set up on the customer's own domain, not ours.

• We help our customers maintain good "hygiene" in their database, so they regularly remove inactive recipients from their sends and of course only send to recipients with valid consent.

That means our own customers using shared IP addresses know the companies they share those addresses with live up to the same high standards they do themselves.

So at the time of writing we have no customers who have asked to send from dedicated IP addresses, since it would only add extra work and greater risk without giving them any advantages.

If, on the other hand, you use a provider where you know in advance that the IP addresses are shared with a large number of companies you know nothing about, then it makes more sense to weigh up whether a dedicated IP address is worth the trouble.

If you want to consider using dedicated IP addresses, you should be able to answer yes to the following 3 questions:

• Does the company send enough mail for a reputation to be built (at least 50,000 emails a month)?

• Does the company have the resources and skills to monitor deliverability and engage with the provider on solving any problems?

• Does the company have a better reputation, better response and a better recipient database than the average at the provider it uses?

If you cannot answer yes to all 3 questions, there is on the face of it no point considering a dedicated IP address for sending emails.

There are many reasons shared IP addresses are the standard

There are a great many technical challenges in delivering very large volumes of email in a short time – and most companies would of course like their emails to reach recipients quickly, including when they send several hundred thousand at once.

Ensuring efficient delivery to many recipients across many sending domains and many receiving domains is, as a rule, easier to manage when the individual sending domains are not sending from dedicated IP addresses.

An individual sender is also less exposed if something goes wrong in their sends when they share IP addresses with others than if they send from their own dedicated IP.

If the mistake happens at a company using shared IP addresses, it only affects a small share of all the email from that IP rather than all of it. At the same time the other companies on the same IP help repair the damage.

With a dedicated IP address the so-called "warm-up process" can also be more awkward, since you start from scratch and only have your own emails to work with. Starting from an IP that already sends plenty of high-quality email means a single company's mail makes up a smaller share of the total volume from that IP, and the warm-up can normally be completed faster.

So our clear recommendation is

1. If you are a customer of ours, you are in such good company that we recommend a shared IP – unless there are quite special circumstances in your business.

2. If you are a customer of another ESP, start by asking them for their recommendation – they know both the volume and the quality of your sends – and then judge for yourself whether you think the answer is objective enough.

3. If you have no confidence at all that you are getting honest answers from your ESP, consider finding another – there are plenty of them...

You can also seek independent advice – the problem being simply that it is very hard to find anyone with up-to-date knowledge of the subject who is genuinely independent at the same time 😀

If you would like concrete input on your situation, we are always ready to give you our view quickly – even if you are not considering becoming a customer.